Is there no easy way to know which one to use.....:(

Hi Sally,

Do these answers help you?

Link: https://www.rocketlanguages.com/your-community/french-vocab/c-est-il-est/

Link: https://www.duolingo.com/comment/176767

Link: https://www.rocketlanguages.com/your-community/conversation-in-french/c-est-et-il-est/

Link: http://french.stackexchange.com/questions/6317/what-is-the-difference-between-cest-and-il-est

This about.com link does a pretty good job of differentiating:

http://french.about.com/library/weekly/aa032500.htm

But if the links still leave the usage a little muddy, here are a few more examples based on the general rules (I think your question is when to use #2 versus #3):

1.  For possessive case, it's c'est à for general case, and il/elle est à if the possessed object is referenced.

Examples:
C'est à moi. - It's mine.
Le livre ? Il est à moi. The book? It's mine.

2.  C'est + adjective or modified adverb - to express a general idea.

Examples:
C'est bon. (It's good.)
C'est vrai (It's true.)

3.  Il/elle est + adjective or unmodified adverb

Examples:
Il est gentil. - It/He is nice.
Il est tard. - It/He is late.

4.  C'est/ce sont + article + noun phrase {noun phrase can include adjective}

Examples:
C'est le nouveau etudiant. (It's the new student).
C'est un hiver froid. It's a cold winter.